A spike in death rates during shifts should not be the determining factor in identifying hospital nurses that may have murdered patients, researchers have claimed.
They warned that focussing solely on hospital attendance data to establish who was working during a shift when large numbers of deaths occurred could lead to miscarriages of justice.
Instead, they called for a wider range of “red flags” – such as drug possession and whether they made colleagues feel anxious – to be considered alongside high death rates when investigating potential healthcare killers.
“It’s really important to acknowledge it will be a cluster of factors and not one individual element that should identify an ‘Angel of Death’ at work in a hospital setting”
The study authors, from Birmingham City University, pointed to Dutch nurse Lucia de Berk who was found guilty in 2003 of murdering seven patients, but was later acquitted after lawyers highlighted the problematic nature of attendance data – which was central to her conviction.
The new study, published in the Journal of Investigative Psychology and Offender Profiling, looked at 16 convicted serial killers in health settings, including Colin Norris who was convicted in 2008 of four murders while working as a nurse at hospitals in Leeds.
Criminologists Elizabeth Yardley and David Wilson wanted to establish whether a certain combination of personality traits or behaviours could be used to detect and prevent nurses that set out to murder patients.
The most commonly occurring traits were higher incidences of death on shift (94%), history of mental instability/depression (63%), making colleagues feel anxious (56%), being in possession of drugs (50%) and seeming to have a personality disorder (50%).
However, they concluded focussing solely on one or two red flags was not likely to be an effective way to identify serial killers. They found that in the case of Mr Norris only two of the indicators were present.
The university has passed its research to the legal team representing Mr Norris, whose case is being looked at by the Criminal Cases Review Commission, and to Greater Manchester Police in relation to three 2011 deaths at Stepping Hill Hospital in Stockport.
Nurse Victorino Chua was charged with the Stepping Hill murders in March 2014 and is expected to stand trial early next year.
Based on their findings, the authors have called for a reassessment of the approaches used by healthcare and law enforcement groups to prevent and detect murderers working in healthcare professions.
Professor Wilson said: “We hope that this research might help hospital administrators to think more critically when they notice a spike in deaths on a particular ward, rather than relying on crude statistical analyses related to particular nurses and their shift patterns. Inevitably, that method will lead to miscarriages of justice.”
Ms Yardley added: “It’s really important to acknowledge it will be a cluster of factors and not one individual element that should identify an ‘Angel of Death’ at work in a hospital setting.”